FIG. 1 is a schematic diagram of an overall architecture of an LTE (Long Term Evolution) system in the related art. As shown in FIG. 1, an LTE architecture comprises an MME (Mobility Management Entity), an SGW (Serving GateWay), User Equipment (called as UE for short) and base stations (eNodeB, called as eNB for short), herein an interface between the UE and the eNB is a Uu interface, an interface between the eNB and the MME is an S1-MME (S1 for the control plane) interface, an interface between the eNB and the SGW is an S1-U interface, and interfaces between the eNBs are X2-U (X2-User plane) and X2-C (X2-Control plane) interfaces. In LTE, a protocol stack of the S1-MME interface is divided into the following protocol layers from bottom to top: L1 protocol, L2 protocol, IP (Internet Protocol), SCTP (Stream Control Transmission Protocol), and S1-AP (S1-Application Protocol). In LTE, a protocol stack of the S1-U interface is divided into the following protocol layers from bottom to top: L1 protocol, L2 protocol, UDP/IP (User Data Protocol/Internet Protocol), and GTP-U (GPRS Tunneling Protocol-User plane).
With wide requirements by users for local services and Internet services, LIPA (Local IP Access) and SIPTO (Selected IP Traffic Offload) are put forward in 3GPP and are used for offloading not only data services from local home networks but also data services from Internet. Simultaneously, for the UE and a core network, a permanent online function needs to be supported, i.e., after a data connection is established, the UE can transmit data to external data networks at any time, the external data networks can also transmit data to the UE. The external data networks involved in this document refer to IP networks which do not belong to a PLMN (Public Land Mobile Network) but are connected with the PLMN, and for example, can be home internal networks or Internet. This function is called as an LIPA@LN (Local IP Access@Local Network) or SIPTO@LN (Selected IP Traffic Offload@Local Network) function. If an L-GW (Local GateWay) which supports LIPA or SIPTO services is arranged on a base station (which can be a macro eNB and can also be a home eNB, i.e., an (H)eNB), this base station is called as a collocated L-GW.
Under a related LTE system, in order to implement an SIPTO@LN function, under a scenario of the collocated L-GW, the base station (which can be a macro eNB and can also be a home eNB) where the collocated L-GW is located needs to report an IP address of the L-GW to the core network through a UE-special message, and a PDN GW (Packet Data Network GateWay) for the SIPTO service will select to use the L-GW address provided by the home base station or the base station ((H)eNB) instead of an address inquired by an DNS (Domain Name Server). Therefore, the (H)eNB needs to carry the IP address of the L-GW in an initial UE message and an uplink NAS transport message.
At present, due to the lack of frequency spectrum resources and the sharp increase of high-traffic services of mobile users, in order to increase user throughput and improve mobility performance, the demand of performing hotspot coverage by adopting high-frequency points such as 3.5 GHz is increasingly obvious, and adopting low-power nodes also becomes a new application scenario. However, since signal attenuation at high-frequency points is comparatively serious, the coverage range of new cells is comparatively small and the new cells and the existing cells are not co-site, hence, if users move between these new cells or between the new cells and the existing cells, frequent handover processes inevitably will be caused, consequently user information will be frequently transmitted between the base stations, a very great signaling shock will be caused to the core network and the introduction of numerous small cellular base stations on a wireless side will be restrained. FIG. 2 is a schematic diagram of an overall architecture of an existing small cellular base station system. As shown in FIG. 2, the overall architecture mainly comprises an MME, an SGW, UE and base stations eNBs, herein the eNBs comprise a master base station (MeNB, Master eNB) and a secondary base station (SeNB, Secondary eNB). An interface between the UE and the eNB is a Uu interface, an interface between the MeNB and the MME is an S1-MME interface, an interface between the MeNB or SeNB and the SGW is an S1-U interface, and an interface between the eNBs is an Xn interface. User data can be issued from the core network to users through the MeNB, and can also be issued from the core network to the users through the SeNB. After the users access to the MeNB, a dual-connection can be implemented by adding, modifying and deleting the SeNB.
Under a small base station system as shown in FIG. 2, since the concepts of the MeNB and the SeNB are introduced, when a user needs to establish LIPA@LN or SIPTO@LN, the core network needs to know an address of the L-GW. For example, under an SCE scenario, due to the deployment of dense small cells, it needs to consider a specific position of a collocated L-GW and how to implement accurate reporting of needed L-GW address information when the MeNB or SeNB changes, thus the core network can implement the LIPA@LN or SIPTO@LN function according to the information. At present, no technical solution for implementing a local gateway service aiming at the scenario with a dual-connection service feature is provided.